sb.append(exp.poll());
while(!exp.isEmpty() && Character.isJavaIdentifierPart(exp.peek())){
sb.append(exp.poll());
}
if(sb.toString().equals("null")){
return new IdentifierObj(null);
}
if(sb.toString().equals("true")){
return Boolean.TRUE;
}
if(sb.toString().equals("false")){
return Boolean.FALSE;
}
return new IdentifierObj(sb.toString());
}
return null;
}